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II.UIVARI)  HEALTH  TALKS 

THE  CAUK  OF  tllll.imKN 
IIV  JOHN   I-OVK'IT  .MOH>K 

l'l{h>KU\ATl\KS  AM)  OlUKH 

(  IlKMK  Al>   IN    KKlDS:     IIILIU   L^E 

AND  AlU  >E 

UV  una  KOLl.N 

IllE  (ARE  OK  THE  ^KI^ 
HV   CHAULt>    JAMES   WIHTE 

THE  (  AHE  Ol    HIE  Sl(  K    IUM)M 
UV    II.HKllX.K  (.MClil    (  t   II. EU 

HIE  TAKE  OK   I  HE  TEEIH 
IIV   (  HAUIK."  AI.IIKUI    ltUA(  KEKl 

ADENOIDS   AND    roN^II> 
HV   AI.<.KUN<i.N   <  Ool.llK.E 

AN    ADEgiME   Dlhi 
ItV   PEKi  V   (.OI.DIHW  \ir  r-ni.l- 

HOW    It)  Wi'lD  IM  1  I   1  Kin-, 
h\    <  lUUl.K-  \  \l.l  i;  (  IIM'IN 


HARVARD  HEALTH  TALKS 


HARVARD  HEALTH  TALKS 


AN  ADEQUATE  DIET 

BY 

PERCY  G.  STILES.  Ph.D. 

AltHiaTANT  PROriSAOH  OF  PHTSIOLOOT 
IN  BAHVAUD  I'MIVEBJilTT 


CAMBRIDGE 

HARVARD    IMVERSITY  PRESS 

1916 


5S'(£>  0^ 


(OJ'YHUillT,    1919 
IIAUVAIII)    IMVUHSITY     rHV_H.H 


Kir»t  ini[>rrv«ii.n.  (K-t"l>rr.  U>10 
vtMtiil  iiiii)r'-"i..ii.  J«iiu»r>-.  19IT 


r,    I  / 


IIAinAHn    HEALTH    TALKS 

]3UKSKNTIN(i  the  siil).staiur  of  soiiu' 

of    the    j)ii))lic   Iccliircs   delivered    at 

.     the  Medical  School  of  Harvard  Univer- 

-V  sity,  this  series  aims  to  provide  in  easily 

"^   accessible  form  modern  and  authorita- 

>    tive    information    on    medical    subjects 

---    of  general   importance.     The  following 

committee,    composed    of    members    of 

the  Faculty  of  ]\Iedicine,  has  editorial 

sui)ervision  of  the  volumes  published: 

EDWARD      IIICKLL\(;      BRADFORD, 
1^         A.M.,    M.D.,    Dean    of   the   FaeuHy   of 
Medicine,   and   Professor  of  Orthopedic 
Surgery,  Emeritus. 

fz   HAROLD    CrAREX(  E    ERNST,    A.M., 
M.D.,  Professor  of  JJacleriology. 

WALTER  BRADFORD  CAXXOX,  A.M., 
^LD.,  (Jeorge  Iligginson  Professor  of 
Pln'siologv. 


AN  ADEQl  ATK  DIET 


ACKNOWLEDGMENT 

Acknowledgments  are  due  to  the  W.  B. 
Saunders  Company  of  Philadelphia  for 
waiving'  contract  rights  in  permitting 
the  publication  of  this  material. 


AN  ADEQUATE  DIET 

The  Problem 

THE  past  few  years  have  been  a 
period  of  great  and  fruitful  activity 
for  the  biological  chemist.  When  one 
surveys  the  results  that  have  been 
amassed,  one  feels  that  the  requisites  of 
diet  are  so  numerous  as  to  make  failure 
in  nutrition  altogether  more  probable 
than  success;  it  seems  scarcely  possible 
that  all  the  known  demands  shall  be  sat- 
isfied. But  as  a  corrective  upon  this  im- 
pression, we  have  before  us  the  fact  that 
the  human  race,  without  scientific  guid- 
ance, has  maintained  through  the  ages  a 
fair  measure  of  health  and  power.  In 
view  of  this  one  may  incline  to  think 
that  scientific  discoveries  in  the  field 
of  dietetics  are  academic  rather  than 
practical. 

11 


HARVARD  HKALTII  TALKS 

A  juiiicial  iiiiiul  will  hold  to  a  middle 
course.  There  need  he  no  diseoura^'e- 
nient  hceaust-  the  re(|nireinent.s  are  so 
many;  on  the  other  hand,  it  is  not  tlie 
part  of  wixlom  to  di>eount  all  that  has 
come  from  the  chenii.sl's  j)atient  labor. 
Kvrn  thoiiuh  mankind  has  survived,  we 
can  conetive  thai  Iniman  standards  may 
he  bettered.  If  thi>  is  true  of  the  race, 
it  is  nmeh  more  eoii>j)i(Uou>ly  true  of 
ill-nouri>hed  indi\"iduals.  ^Ve  nni>t  con- 
.sidcr  in  what  res|)eets  tlic  eon(liti»»ns  of 
nuxlcrn  life  liaNC  modified  hahils  of  dit-t, 
an<i  whctht-r,  in  any  instances,  the 
chaiifjcs  ha\'e  Ix-cii  for  the  worse. 

The  ca>e  i>  paralleled  l»y  that  of  the 
man  who  he^'ins  to  eon>i(ler  the  pitssihili- 
tie>  of  (li>ea>e.  Ihere  are  >o  many  mala- 
dies to  he  thou;;ht  of  that  the  retention 
of  health  seems  like  kee|)in!.,'  o!ie's 
balance  on  a  ti;:ht  rope.  ^'et.  if  the 
pre>er\atioii  of  health  is  really  a  ti;;ht- 
rojM"  performance,  there  is  a  factor  which 
^ives  constant  suj)j)orl,  the  remarkable 
u 


AN  ADEQUATE  DIET 

stability  of  health  in  the  nonnal  subject 
—  his  consiihitioii  —  which  is  like  a 
m'yroscope  in  its  steadying  effect.  Here, 
too,  it  is  rational  not  to  ignore  the  dan- 
gers, but  at  the  same  time  to  recognize 
our  relative  security. 

The  Service  of  Food 

Adequacy  of  diet  is  a  matter  both  of 
quantity  and  composition.  The  two 
phases  of  the  question  can  be  considered 
to  greater  advantage,  if  we  first  briefly 
recall  the  purposes  which  food  subserves. 
These  may  be  said  to  be  three  —  grmvth, 
repair,  and  operation.  It  might  be 
thought  that  repair  would  prove  to  be 
typical  growth,  offset  by  disintegration, 
but  we  have  recent  evidence  that  growth 
has  features  distinguishing  it  quite 
clearly  from  the  processes  of  main- 
tenance. 

In  the  child,  a  moderate  part  of  the 
diet  is  incorporated  into  the  increasing 
mass  of  the  tissues.     Later,  when  these 
13 


HARVARD  HEALTH  TALKS 

are  no  loiif^er  on  the  increase,  a  rather 
small,  hut  perfectly  detinite,  fraction  of 
the  food  taken  is  still  devoted  to  com- 
pensation for  their  wear  and  tear.  But. 
first  and  last,  the  major  part  of  the  food 
serves  for  the  operation  of  the  mechan- 
i>m.  and  can  he  correctly  described  as 
fuel.  The  hody  may  he  likened  to  a 
I>o\ver-house  which  had  to  he  huilt  from 
certain  materials,  nuiintained  hy  other 
supplies,  hut  which  is  operated,  day  hy 
day,  at  the  cost  of  vast  ((uantities  of 
coal.  It  is  clear  that,  in  the  lon^  run, 
tlu'  coal  ma\'  ^'reatly  outwei^^'h  the 
nuichinery  and  the  .structure  which 
houses  it. 

Our  anaht^'y  is  faulty,  of  course,  par- 
ticidarly  in  that  tlu-  p()Wer-liou>e  is  not 
operated  luitil  it  has  i)een  completed, 
while  the  human  or^^anism  is  active  from 
early  emhry(»nie  life,  hurnin^  fuel,  and 
setting'  the  ener^'y  free  while  its  construc- 
tion ^oes  steadily  on.  'I'Imtc  is  an»>ther 
respect,  however,  in  which  our  comj)ari- 


AN  ADEQUATE  DIET 

son  is  entirely  justified.  For  purposes  of 
construction  it  is  necessary  to  have 
precisely  the  rif,'ht  materials;  among 
fuels  there  is  a  greater  possihility  of  sub- 
stitution. Just  as  the  |)lan  of^the  builder 
calls  for  wood  in  one  i)lace,  steel  in  an- 
other, and  glass  in  a  third,  so  the  devel- 
o])ment  of  the  human  frame  recjuirt^s  a 
larger  number  of  tiistinct  and  s])ecific  sup- 
plies than  we  realized  a  short  time  ago. 

Plainly,  the  diet  must  furnish  material 
adapted,  first  to  make,  and  always  to 
maintain,  the  sum  of  all  the  tissues.  In 
other  words,  it  must  bear  a  certain  like- 
ness to  the  body  it  is  to  nourisli.  but 
it  need  not  be  rigidly  similar,  for  the  cells 
have  a  caj)acity  to  transform  certain 
comi)ounds  into  others.  Thus  it  is  pos- 
sible to  make  haemoglobin,  the  valuable 
red  pigment  of  the  blood,  from  vegetable 
substances^  whicli  seem  quite  remote 
from  it  in  their  chemical  nature.  A 
hundred  years  ago  physiologists  thought 
that   animals   had   to   obtain   all   their 


HARVARD  HEALTH  TALKS 

ncrt'ssary  ((tiistitiuMits,  n-ady-fonned, 
fnjin  tlif  j)laiit  world.  This  is  by  no 
nu'an>  tlic  cax-;  many  syiitlu'st'S  aro 
carrii-d  out  Ity  animal  tissues.  \(.'t  the 
(■on>tru(tivr  ])o\vt'r  lias  its  limits,  anil 
>onutimcs  IIk-m-  arr  unrxiHctrdly  mani- 
fotcd. 

'I'h adhk )N ai.  Standauds 

There  ar«'  t  wo  slandard>  l>y  wliich.  in  the 
past,  ilittN  lia\"e  Iteen  a])|)raised.  One  of 
these  is  the  fuel  vahie.  It  !>  (lear  that 
tiiis  i>  niie  criterion  \\hieli  must  he  satis- 
fied. tiioUL'h  it  does  imt  hy  itself  show 
that  a  ration  is  snljieieiil;  it  is  merely  a 
m«'asure  of  (|iiantity,  and  not  an  indiea- 
tion  of  siiitahh-  (  om|)osiii(.ii.  The  unit 
of  fuel-\alue  i.s  tile  lar^e  calorie,  winch  is 
primarily  a  .standard  <juantity  of  heat. 
Since  one  f.iiiii  (if  elielL'N'  can  he  c<tn- 
\erled  into  another,  tiie  calorie  may 
stand  not  only  for  heat  hut'  for  iiorh, 
which  is  the  >,•<•(. ntl  irreat  item  in  the 
dynamic  <tut|)nt  of  the  hoily. 


AN  ADEQUATE  DIET 

The  heat  value  of  an  average  diet  may 
be  set  down  as  twenty-five  hundred 
calories'prr  dtcm.  This  is  for  an  individ- 
ual doing  hut  little  physieal  work.  The 
allowanee  for  sueh  subjects  may  be 
scaled  down  to  two  thousand  but  must 
be  increased  for  those  whose  labor  is 
heavy.  Farmers,  the  world  over,  seem 
to  require  about  thirty-five  hundred 
calories.  A  maximum  in  the  vicinity  of 
seven  thousand  has  been  recorded  for  the 
Maine  lumberman.  It  is  interesting  to 
note  that  an  alcohol  lamp,  burning  a  pint 
of  its  proper  fuel  in  twenty-four  hours, 
is  as  large  a  source  of  heat  and,  poten- 
tially, of  other  energy  as  an  average  man. 

Protein 

The  second  standard  by  which  diets  have 
been  judged  is  their  protein  content. 
Proteins  are  the  compounds  in  our  foods 
which  most  nearly  resemble  the  leading 
constituents  in  muscles,  glands,  and  liv- 
ing tissues  generally.     There  is  no  doubt 


HARVARD  HEALTH  TALKS 

of  tluir  peculiar  iinj)ortanci'  for  growth 
and  for  the  iipkcci)  of  the  or^'an.s.  l)ut  it 
has  i>rove(l  dillicult  to  fix  upon  tlu>  ideal 
amount  for  these  services.  Most  people, 
choosing  their  food  with  uo  thought  of 
its  nature  and  guided  oidy  by  appetite, 
take  from  two  to  tliree  ounces  (fifty-six 
to  eighty-four  grams)  daily.  It  has  com- 
monly heen  held  that  a  M'lection  so 
widely  concurred  in  caiuiol  he  far  wrong. 
Are  We  always  >afe  in  assuming  that  the 
average  j)ractice  is  the  hest  ])os.sil)le  ? 

It  may  he  urgecl  that  the  lower  ani- 
mals haN<' no  guide  hut  instinct.  If  they 
are  Well  nourished,  cannot  man  he 
trusted  to  clio«>sr  his  fctod  'l  This  does 
not  necessarily  follow.  Man  '*  has 
sought  <iut  many  in\tnt inns,"  and  in- 
stinct hccomo  an  unceitain  counsclhtr 
when  in  the  mi(Ut  of  artificial  conditions. 
It  is.  in  fact,  true  of  domestic  animals 
that  the  agriculturist  may  select  a  ration 
that  i>  prohaMy  hd  fcr  for  them  than  any 
<»f  th<-ir  own  choosing. 


Is 


AN  ADEQUATE  DIET 

We  may  assume  that  our  remote  an- 
cestors had  a  restricted  clioice  of  food, 
that  they  were  frecjuently  on  short  com- 
mons, and  that  they  were  seldom 
tempted  to  eat  merely  to  enjoy  varied 
flavors.  A])petites  adapted  to  their  lot 
would  lead  to  over-consumption  if  in- 
herited hy  descentlants  having  access  to 
food  of  many  kinds.  This  argument 
may  be  applied  either  to  the  question  of 
total  quantity  or  to  that  of  the  protein 
allowance.  Sylvester  Graham  thought 
that  a  meal  should  consist  of  but  one 
course,  and  there  is,  j)erhaps,  no  better 
safeguard  against  over-eating  than  this 
simple  principle. 

If  proteins  were  of  no  use  but  for  con- 
struction like  the  bricks,  tiles,  and  glass 
brought  to  our  hypothetical  power- 
house, there  would  evidently  be  no  value 
in  an  excess  over  the  current  require- 
ment. They  are  actually  more  adapt- 
able than  this;  they  are  more  like  lum- 
ber which  can  be  turned  to  account  as  a 

1!) 


HARVARD   HEALTH  TALKS 

fiu'l  supply  if  not  iicedt'd  for  building 
niaU'rial.  A  strong;  suggest  ion  is  con- 
Vi'Vi'd  tluit  siicli  list-  of  proteins  is  some- 
what extrava^'ant,  and  this  is  prohahly 
just.  The  objections  to  tlie  (•onsuini)tion 
of  much  protein  food  nuiy  he  concisely 
stated. 

Al  T<>-L\TOXI(ATI()N 

J'lu'se  ol»jections  fall  into  two  (lasses. 
I'ir>t,  we  lia\"e  to  reckon  with  certain 
peculiarities  of  jtroteins  when  they  are 
acted  upon  in  the  alimentary  canal.  All 
types  of  f(»od  under;.:o  decomposition  — 
as  distin^'uished  from  di^stion  while 
in  the  intoline.  The  extent  of  the 
chani^'es  i.>  prohahly  ^M'eatot  in  the  case 
of  the  >u^'ar>.  and  lea>t  with  the  fats. 
I'roteins  are  intermediate  in  the  de^'ree 
of  their  decomposit i«>n.  hut  it  is  \\v\\ 
e.stahlisln-d  that  the  j)roduct>  arising  are 
jxculiarly  harmful.  (  Crtain  of  the  ])ro- 
ducts.  carried  far  and  wide  by  the  cir- 
culation, have  power  to  injure  the^M-neral 
■JO 


AN  ADICQIATE  DIKT 

health.  Any  form  of  disturhaiu*'  (liic  to 
them  may  be  called  a  symptom  of 
anto-inioxicatiou . 

Certain  mild  effects  have  lon^  been 
referred  to  this  source.  Amon^  them 
hjive  been  headache,  drowsiness,  and 
quick  susceptibility  to  fatij^ue.  It  is 
now  believed  that  much  graver  ills  niay 
originate  from  abnormal  decomposition 
in  the  tract,  and  the  entry  of  poisons 
into  the  system.  Troubles  with  the 
joints,  anaemia,  and  serious  nervous 
disorders  may  be  mentioned.  It  is  clearly 
important  in  all  such  cases  to  keep  down 
the  protein  of  the  ration.  The  decom- 
positions which  do  so  much  luinn  result 
from  the  activities  of  the  swarming 
micro-organisms  of  the  intestine.  Our 
natural  defense  is  the  j)romi)t  absor])tion 
of  the  products  of  digestion  and  the 
consequent  absence  of  a  lagging  surplus. 

In  addition  to  the  drawbacks  of  a 
protein  excess  in  the  canal,  we  must 
recognize    that    bad    eU'ects    nuiy    arise 


HARVAHI)   HKALTH  TALKS 


from  Micli  rxccss,  even  th<)iij,'l»  thf 
pntteiii  l>o  pcrft'ctly  <li^^'>lc(l  and  al)- 
sorlx'cl.  Ill  the  normal  (•oiir>r  of  «'\«'nts, 
all  tin-  >tar(h.  and  tlu'  scvrral  simars, 
which  \\r  cat  \\  ill  he  offered  to  the  tissues 
in  the  form  of  .simj)h'  >u;^Mr>  « two  or  three 
variclioi.  All  the  fat  of  our  food  will 
li^nirc  a^'ain  as  fat  when  transferred  to 
the  Mood,  ^^'hen,  later,  su^'ar>  an<l  fats 
are  l)urn«(l  ^  oxidized  s  under  the  u>ual 
conditions  of  life,  only  two  products 
arise.  These  are  carhon  dioxid  and 
water.  I  heir  remo\  al  is  a  siuiple  mat- 
ter: the  carlxtii  didxid  pasNcs  (»>il  in  the 
hrealh;  the  water  hhnds  with  a  much 
lar^^-r  \iilunie  which  is  always  pas>in<,' 
fhrouuh  the  liody,  an<l  is  cared  fur  l»y  all 
the  channels  of  excrct  ion. 

It  is  otherwise  when  |)rotcin  is  treated 
as  a  fuel,  ('arl)on  dioxid  and  wati  r  are 
mdecd  foi-nicd,  l»uf  other  ]»ro(lucls  iu- 
e\italtly  accompany  them.  These  ha\e 
to  lie  dealt  with  hy  tin-  kidneys,  ^\'e 
may  rou^'hly  liken  the  hurninu  of  su^'ar 


AN  ADKQIATE  DIET 

and  fat  to  tlio  use  of  ^ms  for  fuel;  wliilc 
[)rot('in  scciiis  more  like  coal.  \Vlu'n  we 
l)urn  gas,  we  liavc  only  to  look  to  our 
draught  or  ventilation;  a  coal  fire  leaves 
us  its  ashes  as  an  additional  care. 

Enough  has  heen  said  to  justify  much 
of  the  present  day  teaching,  to  the  eilVct 
that  definitely  high  protein  diets  are 
undesirable.  It  is  nearly  as  plain  that 
nutrition  may  sutler  from  a  scant  protein 
su])ply.  It  is  by  no  means  established 
that  the  minimum  is  the  optinnim. 
Doctor  Samuel  J.  Meltzer  has  discussed 
this  (piestion  from  an  original  stand- 
point, and  it  may  be  worth  while  to 
recount  his  argument. 

When  an  engineer  plans  a  bridge,  he 
docs  not  aim  to  have  its  strength  just 
sufficient  for  the  strain  it  will  ])robably 
have  to  bear,  lie  designs  it  to  be  nuich 
stronger  than  this.  If  he  makes  it  cap- 
able of  sustaining  three  times  the  antici- 
pated load,  the  "  factor  of  safety  "  is 
said  to  be  three.  In  a  very  real  sense, 
23 


HAR\ARI)  IIKAI/rH  TALKS 

tlu'  liuiiKin  l)()(ly  lias  its  factors  of  safety, 
and  they  arc  gcncrtnis  oiu-s.  For  ex- 
aini)K',  a  man  has  two  lun^s,  hut  can 
exist  witli  one.  lie  can  survive  the  h)ss 
of  one  kidney.  His  aUnientary  canal 
can  he  nnich  shortened;  many  hrlieve 
that  he  would  he  hetter  off  without  the 
colon. 

Doctor  Melt/er  states  these  facts,  and 
then  asks  wlM-lher  any  one  can  seriousl\- 
maintain  that  a  man  is  hetter  olT  with 
his  or^ians  so  reduced  than  with  the 
entire  e(juij)ment.  If  it  is  desirahlf  to 
have  or^Mns  which  are  not  strictly  indis- 
pensahle,  is  it  not  reaxmahlc  to  ^'ive 
them  somewhat  more  than  a  Itari-  mini- 
nuim  of  Work  to  do  ?  ('erlaiiily  no  one 
will  claim  thai  the  ht^l  courx-  f«»r  the 
musclo  in  ^'eneral  i>  to  u>«-  them  no 
more  than  is  ah-«oluteIy  iifcrs>ary.  Is 
it  then  l»<>t  to  s|)are  the  alimentary 
tract,  the  li\'er,  and  the  kidneys  r\Try 
whit  that  can  he  >uhlractrd  from  their 
duties  ?        riir     reasoning     is     inu'rnious 

2  J 


AN  ADEQUATE  DIET 

and  suggostive,  tliough  i)erliaps  not 
unanswcrahU'. 

The  danger  lo  be  appreliended  from 
too  little  protein  is  in  the  nature  of  a 
general  decline  of  vitality  and  resistance. 
The  results  may  be  like  those  of  poverty, 
or  they  may  recall  the  lack  of  initiative 
and  vigor  characteristic  of  certain  ill-fed 
races.  But  it  is  probably  true  tliat  the 
prevalent  error  is  over-consumption. 
This  is  more  markedly  the  case  with 
men  than  with  women,  and  most  fla- 
grantly with  those  in  easy  circumstances 
wlio  are  much  in  hotels  and  clubs. 

The  nutritive  worth  of  the  proteins  in 
various  foods  is  not  perfectly  uniform. 
It  is  generally  l)elieved  that  those  in 
meat,  milk,  rice,  and  potato  are  of  a 
superior  type.  One  or  more  of  these 
foods  will  enter  into  any  ordinary  diet, 
and  the  danger  of  suffering  from  an 
unwise  selection  of  proteins  is  rather 
remote.  The  emphasis  seems  to  be 
shifting  from  the  specific  merits  of  par- 


HARVARD  IIKALTII  TALKS 

ticular  ])r()t(ins  to  incciualitit's  of  food 
^■alll(  s  arising  from  the  prt'st'ncf  or  lack 
of  minor  (•oIlstilll('Ilt>^.  Wo  must  pass 
on  to  tlii>  >ul»j«'(t . 

Tin:  \'\i.i  i;  ok  MiNoit   Con- 

STiriKNTS 

TluTc  arc  l»ut  fiw  articles  of  human  cou- 
sumj)ti<>n  which  <lo  tiol  pro\c,  ujkhi 
chemical  iuvotii^Mtiou.  to  he  mixtures 
of  many  c(>mj)ouii<l>.  Mncu  our  drink- 
ing water  contaiu>  >alts  and  other 
bodies  in  sohition.  ( "ane->>ii:ar  comes  as 
near  hein^'  a  >inirle  |)ure  comjxtund  as 
anything  we  eat.  and  this  it  is  our  i)rac- 
tice  to  comhine  with  (tther  foods.  Su^'ar 
iuis  heeii  condemned  for  the  Acry  reason 
that  it  is  a  purifitd  and  homoi^eneoiis 
comi)ound,  and  therefore  not  a  "  natu- 
ral "  food.  This  does  not  ^eem  an  im- 
I)ressi\c  aru'umt  III .  so  luni,'  as  there  are 
many  contract  ini:  foocU  m  the  diet, 
hut  it  is  certain  that  we  cannot  ^'o  on 
indefinitcl.N'  reducing'  the  numher  of  com- 


AN  ADKC^IATE  DIET 

pounds  without  sooner  or  later  exclud- 
ing something,'  essential  to  nutrition. 

The  nn'nor  constituents,  in  which 
there  is  so  nuich  interest  at  this  time,  are 
partly  organic,  and  partly  mineral.  'J'he 
belief  that  mineral  sui)plies  in  a  certain 
variety  are  necessary  to  health  is  not 
new.  During  growth  it  is  as  truly  re- 
quisite to  provide  these  as  to  furnish  the 
proteins  themselves.  The  ash  left  he- 
hind  when  milk  is  first  evaporated  and 
then  burned  has  been  shown  to  be  mar- 
vellously adapted  to  its  .special  service. 
the  production  of  standard  tissue.  The 
organic  ingredients  of  the  accessory 
class  deserve  rather  full  treatment. 

They  are  useful,  first  of  all,  because  to 
a  great  extent  they  determine  the  ])ala- 
tability  of  food.  This  is  very  far  from 
being  merely  an  aesthetic  consideration. 
iMeals  must  be  relished  if  they  are  to  be 
well  digested.  Proteins,  starch,  and  fats 
in  pure  condition  are  tasteless,  and  aside 
from  the  sweetness  of  the  sugars,  all  the 
27 


HARVARD  HEALTH  TALKS 

numlH'rU'ss  flavors  wr  cnjov  i\ro  due  to 
the  accessories,  mineral  and  organic' 
The  latter  are  inucli  the  more  important, 
for  the  salts  are  odorh'ss.  Some  of  the 
extractives,  notahly  those  in  meat, 
directly  stimnlate  the  linin'^  of  the 
stomach  x)  as  to  promote  the  secretion 
of  the  j^Mstric  juice. 

But  the  accessories  are  not  sij^'nificant 
for  (iip>tion  alone;  thev  have  a  most 
.striking  relation  to  nutrition.  Their 
I)resence  in  suitable  assortment  is  im- 
I>erative.  The  recognition  of  this  fact 
is  clearing  uj)  many  maltcr>  that  have 
l)»'en  })erplcxing.  It  has  heen  hard  to 
account  for  the  ohvious  ine(|uality  in 
nutritive  valu<'  whicli  i>  often  (h-mon- 
strated  for  diet>  c(|ui\alfnt  in  calories 
and  protein  content.  It  ha>  been  clearly 
sliou!i  that  of  t\v»»  >uch  (liet>  one  may  he 
am))le  for  all  j)uri)o^e>.  and  the  other 
ina<le(juate,  simply  hei  au«>e  the  iir>t  con- 
tains mimite  (piantitio  of  >ul)->tance> 
not  found  in  the  .second. 


AN  ADEQUATE  DIET 

Reforencc  has  hecn  made  to  Sylvester 
Graham.  We  shall  do  well  to  examine 
one  of  his  chief  doctrines  which  is  enjoy- 
ing somelhing  of  a  revival  in  our  day. 
The  flour  which  hears  the  name  of  (Ira- 
ham  contains  all  parts  of  the  wheat 
kernel,  the  husk  as  well  as  the  interior. 
This  reformer  taught  that  hy  rejecting 
tlie  Inisk  we  might  fail  to  obtain  some 
essential  fraction  of  the  food.  This  was 
a  shrewd  induction.  It  has  been  defi- 
nitely i)roved  that  when  the  envelope  or 
pericarj)  of  rice  is  discarded,  the  grain 
ceases  to  be  a  complete  food  for  pigeons. 
An  active  ])rincii)le  can  be  ])rei)ared 
from  the  j)ericarp  which  will  ])erfectly 
remedy  the  deficiency  when  suj)i)lied  in 
minute  quantities. 

What  goes  wrong  in  the  economy  of 
the  i)igeon  which  is  restricted  to  a  diet 
of  polished  rice  ?  The  question  can  be 
answered  with  some  precision.  The 
compound  which  the  ration  fails  to 
furnish  is  needed  most  urgently  by  the 
29 


HARVARD  HEALTH  TALKS 

nerves.  If  it  is  not  alTortled  ])y  the  food, 
a  liniitt'd  supply  can  l)e  liad  fn)ni  otiier 
tissues  of  the  l»o<ly,  hut  at  a  heavy  cost: 
the  structures  U'vied  uj)on  disintegrate. 
It  is  as  tliou^h  ))olls  were  removed  from 
one  niacliine  to  n'pair  another  witli  tlie 
result  that  the  lir>t  fell  to  i)iece>.  \Vhen 
the  ner\i'S  can  no  longer  he  sustained, 
even  l)y  this  ruinous  j)roce>is.  they  hc- 
eome  definitely  diseased. 

ni-in-IiiHi 

The  failure  of  nutrition  in  the  pi^'eon  is 
i)elic\f(l  to  coriopond  rather  clox-ly 
with  the  di>ca><-  of  man  known  in  the 
Ka>t  as  l»cri-l»eri.  I'cople  rotrieted  hy 
hahitat  and  po\'erty  to  a  monotonous 
dirt  ar«'  ><)m(lime>  t»l»^tr\t(l  to  lose 
raj)idly  in  wciuhf  and  >trcii^th.  and  then 
to  (h-veloj)  acute  nervdU"*  lesious  ijKily- 
neuriti>!.  Ih-ri-heri  ha^  al\\ay>^  Iteen 
hani^hed  fruni  coiunnnnties  iu  which  the 
foo(l-Nuj»j)ly  has  hecduie  more  aiuple  and 
inclusive. 


AN  ADEQUATE  DIET 

Scurvy 

Similarly,  it  has  hocn  hclicvcd  that 
scurvy  is  a  deficiency  disease.  The 
chronicles  of  ex])lorers  ahoiind  in  in- 
stances of  this  distressing  malady.  The 
victims  have  been  ])roslrated,  have  suf- 
fered intensely  from  sore  mouths,  have 
had  haemorrhages  under  the  skin,  friable 
bones,  and  a  long  list  of  other  symptoms. 
Various  articles,  such  as  lime-juice  and 
potatoes,  have  seemed  to  l)e  efficacious  in 
warding  off  and  relieving  scurvy.  Some 
have  contended  that  scurvy  is  a  form  of 
poisoning  due  to  products  of  decomposi- 
tion develoi)ing  in  the  food.  It  seems 
more  in  accord  with  the  facts,  however, 
to  assume,  not  that  the  food  has  come 
to  contain  a  poison,  but  that  some  valu- 
able constituent  has  disintegrated.  The 
lime-juice  or  the  ])otato,  then,  does  not 
convey  the  antidote  to  a  poison,  but 
rather  an  ingredient  similar  to  that  one 
which  has  been  lost. 

31 


HARVARD  HEALTH  TALKS 

VITA^^I^■E.s 

It  has  been  proposed  lo  call  tin-  valuahlf 
.sul)slaiut's  for  want  of  wliich  IxTi-hcri, 
scurvy,  and  other  disorders  arise,  l»y  the 
name  of  rlftuninfs.  An  mninf  is  a  nitro- 
genous conij)ound  of  a  certain  type, 
while  the  j)refix  suggests  that  a  vilaniine 
is  such  a  conij)ound  as  is  necessary 
to  life.  riie  ol)j«'cti()U  lias  heen  raised 
that  the  term  is  too  >j)ecilic;  we  do  not 
know  that  all  .su<h  hodies  are  amines, 
nor  even  that  they  are  nitro^'enous;  it  is 
prohahle  that  some  of  them  are  neither. 
Hence  it  seem.s  lutler  to  call  them  acces- 
sory substances,  and  not  to  insist  on  a 
chemical  cla.ssilication. 

L<'t  us  now  consider  (|uite  fully  in  what 
ways  the  human  syslcin  may  fail  to  re- 
ceive any  (»f  the  supi)lie.s  necessary  to  its 
Welfare.  The  ,sU;^M,'est  ion  from  Iteri-heri 
is  to  the  effect  that  this  may  hai)pen 
wlu-n  the  selection  of  food  is  t(»o  re- 
stricted.       I'urthermore,     we     recoj^ni/.e 


AN  ADEQUATE  DIET 

the  possible  inij)ainiient  of  food-values 
by  refining.  But  we  may  repeat  that 
there  can  be  no  serious  objection  to  this 
refining  when  it  is  applied  only  to  a 
moderate  part  of  the  diet. 

A  condition  which  many  hold  to  be 
analogous  to  beri-beri  is  the  grave  dis- 
order, pellagra.  This  is  a  disease  of  grad- 
ual development.  The  early  symptoms 
are  confined  to  the  skin;  later,  the 
manifestations  are  widespread,  and  at 
the  last  violent  insanity  may  supervene. 
Pellagra  has  long  been  recognized  in 
Mediterranean  coinitries,  and  its  pres- 
ence in  our  own  Southern  States  is  now 
frequently  reported.  It  is  generally 
found  to  have  attacked  those  whose  food 
is  of  but  few  kinds.  Like  beri-beri,  it  is 
usually  arrested  if  the  diet  is  enriched. 
Meat  and  milk  are  especially  beneficial. 
It  is,  however,  not  yet  certain  that  pel- 
lagra is  a  deficiency  disease.  When  a 
number  of  people  closely  associated 
suffer  from  a  disorder,  the  first  impres- 

33 


HARVARD  HEALTH  TALKS 

sion  is  tliat  it  has  spread  among  them  as 
an  infection;  hut  we  liave  also  to  con- 
sider that  it  may  he  tlie  uniformity  of 
their  environment  and  diet,  ratlier  than 
tlieir  ct)ntact,  which  lias  led  to  like  effects 
in  many  individuals.  These  allernalives 
in  the  ca>e  of  pellaura  are  still  heing 
debated. 

( '<)f)KiN(; 

So  far  we  ha\('  dwelt  ujK»n  two  concej)- 
tions:  fir>t.  that  nutrition  nuiy  suffer 
iron\  a  narrow  selection  of  food;  second, 
that  lon^'  keei)ing  may  roult  in  a  lo>s  of 
accessories.  Are  there  >till  other  condi- 
tions to  he  reckoned  with  ?  It  may  i)roj)- 
erly  he  asked  whether  cookinu  may  not 
have  some  dama^'ini:  influence.  There 
arc  those  who  acti\ely  ad\(»cate  un- 
cooked rations,  and  who  iheniseKi  s  live 
on  fruits,  mils,  aiid  ^'reeiis,  j)erlia|)s 
making  use  aKo  of  milk.  Here,  as  in 
man\'  another  extreme  teaching,  we  can 
discover    a     measure    of    truth.       Some 


.{•1 


AN  ADEQUATE  DIET 

valuable  substances  in  food  may  very 
probably  be  destroyed  by  strong  heating. 
But  we  need  not  hasten  to  join  such  a 
cult.  The  most  that  we  are  recjuired  to 
concede  is  that  we  ought  to  eat  a  fair 
amount  of  raw  footl.  We  need  n(^t  forego 
the  great  advantages  which,  in  the  case 
of  many  articles,  are  .secured  by  cooking. 
These  include  develoi)ment  of  flavor,  the 
breaking  open  of  vegetable  cells  to  per- 
mit the  digestion  of  their  contents,  and, 
above  all,  the  destruction  of  disease- 
producing  germs.  Cooking  greatly  ex- 
tends the  range  of  our  choice,  and  we 
have  been  urging  all  along  that  safety 
is  found  in  inclusiveness. 

Faulty  Assimilation 

When  nutrition,  in  spite  of  the  best  and 
most  varied  fare,  falls  short  of  success, 
we  may  think  of  still  another  possibility. 
Just  as  foods  may  be  imi)aired  by  radical 
or  gradual  decomposition  ))efore  they  are 
eaten,  so  they  may  deteriorate  in  a  dis- 
3.5 


HARVARD  HEALTH  TALKS 

u.strous  inaniuT  lu'forc  being  absorhod. 
The  slip  may  not  conic  lu'twccn  the  cup 
and  the  lip,  but  between  the  lip  and  the 
circulation.  We  have  often  to  remind 
ourselves  that  what  is  within  the  intes- 
tine is  not  yet  within  the  body;  it  is 
merely  in  contact  with  its  surface,  and 
subject  still  to  accidental  altiTations. 

Finally,  it  i>  ]>os>ible  that  all  the  ma- 
terials needed  for  the  nutrition  of  the 
Ixxly  may  be  presente«l  to  the  cells  whose 
duty  is  to  absorb  them,  and  the  last  step 
may  fail  to  be  taken.  In  other  words, 
there  may  l)e  faulty  assiuiilation.  When 
a  baby  does  not  do  well,  this  is  probably 
the  case.  The  fact  that  tin*  milk  was 
originally  adecjuate  may  be  shown  by  the 
successful  milrition  of  other  infants 
ha\ing  the  same  supj)ly.  Non->uccess,  in 
a  j)arlicular  instance,  may  be  due  either 
to  an  unfortunate  type  of  intestinal 
decom])o.sition  or  to  deficient  ab>orption. 

\\hile  we  ha\'e  to  admit  this  possi- 
bility,   we   ought    at    the    same    time    to 


AN  ADEQl'ATE  DIKT 

point  out  liow  loose  arc  many  statements 
commonly  made  re^ardinj^  variations  in 
assimilation.  It  is  often  suggested  tliat 
one  person  gets  "  more  of  tlie  goodness 
of  his  food  "  than  does  another.  In  this 
way  the  attemj)t  is  made  to  explain  why 
reputed  large  eaters  sometimes  remain 
thin,  lint  the  evidence  goes  to  show  that 
individual  differences  between  persons  in 
fair  health  are  never  striking.  That  is  to 
say,  they  are  not  large  in  a  quantitative 
sense. 

Percentile  Absorption 

The  alimentary  canal,  even  when  seri- 
ously mistreated,  usually  retains  a  high 
degree  of  efficiency.  Unless  food  is  of 
a  very  intractable  character,  not  more 
than  ten  per  cent  goes  to  waste.  Some- 
times the  loss  by  imperfect  absorption  is 
as  little  as  five  per  cent.  It  is  therefore 
absurd  to  talk  of  improving  absorption 
by  fifty  or  a  hundred  per  cent.  Little 
absolute  gain,   in    this   respect,   can   be 

37 


HAinARI)  IIKALTH  TALKS 

hoped  for  as  a  result  of  j)rolonged  masti- 
cation or  any  otlicr  special  ])ractice. 
Nevertheless,  as  we  have  iniplietl  above, 
a  slight  iniprovenient  as  measured  by 
percentage  may  have  a  material  in- 
fluence on  nutrition,  some  accessory 
which  previously  escaped  the  organ- 
ism being  secured  for  its  service.  It 
would  not  be  wise,  however,  to  make 
much  of  this  suggestion,  which  is  frankly 
speculative. 


^IM.M  AHV 

It  will  be  well  now  to  recaj>il ulate  the 
points  which  ha\'t'  gone  before.  The 
diet  must  satisfy  Ihe  fu»'l  rc(|uir<nifnt  of 
the  body.  It  nnist  furni>h  suitable  pro- 
teins, and  it  is  belter  that  these  should 
be  derived  from  numerous,  rather  than 
a  few  scjurces.  (  This  d(»e.>,  not  mean  that 
a  single  meal  should  be  com|)le\,  but 
tliat  there  should  be  \ariety  from  day  t,o 
day.)  MijK-ral  matter  is  a  delinite  need. 
An  unknown  mimber  of  aeee>>ories  are 
;5s 


AN  ADEQUATK  DIKT 

required  if  all  is  lo  ^o  well  throu^'h  lon^^ 
periods  of  time.  It  may  not  at  i)resent 
be  possible  to  know  in  every  instance 
whether  a  given  food  possesses  virtue  by 
reason  of  its  organic  or  its  mineral 
composition. 

Perhaps  we  need  not  add  further  to  the 
list  of  absolute  recpiirements;  but  there 
are  other  desiderata.  Some  of  tliese  are 
so  obvious  that  they  may  be  i)assed  over 
with  a  word.  The  importance  to  us  of 
food  which  api)cals  to  the  appetite 
should  be  i)lain  without  an  argument. 
It  may  be  said  tliat  we  should  eat  what 
we  like.  Our  liking  is,  as  a  rule,  the 
guarantee  of  digestion.  Yet,  recalling 
our  plea  for  inclusiveness,  we  are  bound 
to  add  at  once  that  they  are  fortunate 
who  like  a  great  many  kinds  of  food. 

Roughage 

\Ve  speak  of  certain  foods  as  relatively 

indigestible.     What  we  usually  mean  is 

39 


HARVARD  HKALTH  TALKS 

that  tlu'  articles  i!i  (jiu'stion  cause 
iliscomfort  or  downright  disturhanccs. 
Many  ])c()i)lc  have  iKTliaj)s  never  re- 
flected that  a  certain  amount  of  totally 
indigestible  matter  may  he  harmless,  if 
not  advantageous.  The  distinct  useful- 
ness of  a  mtKlerate  (juantity  of  husk  and 
woody  (ihre  is  p'lUTally  aHirmed.  (iranl- 
ing  that  we  may  extract  certain  acces- 
sories from  such  a  source,  we  nuist  still 
admit  that  the  mass  of  the  material 
makes  no  contribution  to  the  body.  It 
has  been  spoken  of  as  "  ballast,"  and  also 
as  *'  roughage." 

In  what  ways  can  indigestible  matter 
be  helj)ful  ?  The  assumption  is  com- 
monly made  that  it  stimulates  the  intes- 
tinal lining  b\'  direct  contact  an<l  i>ro- 
vokes  a  \igorous  nni>cular  reaction. 
This  may  not  be  |)rcciscly  the  way  in 
which  roughage  corrects  the  evil>  of  con- 
stipati(»n.  but  tlnre  i>  little  doubt  that 
the  general  influence  is  good.  \\  e  may 
suj)i)ose  that  such  material,  as  it  is 
in 


AN  ADEQUATE  DIET 

moved  along  the  alimcnlary  canal, 
catches  and  takes  with  it  acciiniulations 
which  might  not  otherwise  have  the 
necessary  hulk  to  be  acted  u[)on.  Its 
function  would  thus  he  amusingly  like 
that  of  the  saw-dust  which  the  janitor 
throws  uj)on  the  floor  before  sweeping. 

It  may  be  j)ossible  to  include  too  much 
roughage  in  the  ration,  but  the  opposite 
practice  is  probably  more  common.  The 
principal  substance  which  can  figure  in 
this  role  is  cellulose,  an  indigestible  com- 
pound furnished  most  abundantly  by 
fruits  and  coarse  vegetables.  The  agar- 
agar  preparations  often  used  to  over- 
come constipation  are  substitutes  for 
cellulose,  or,  in  its  presence,  may  supple- 
ment and  reinforce  it. 

In  this  connection  it  should  be  pointed 
out  that  the  deliberate  choice  of  foods 
containing  a  nuixinuim  of  innutritions 
matter  is  favorable  to  weight  reduction, 
for  rations  distinguished  by  bulk  rather 
than  actual  food  value  may  fairly  well 

41 


HARVARD  IIKALTH  TALKS 

ai)pea.se  the  appctito,  while  failing  to 
iiu'ft  tlic  full  lU'cds  of  the  tissues.  The 
fat  man  can  rej)laee  his  bread  and  butter, 
potato,  pastry,  and  candy  with  salads, 
greens,  and  fruits,  but  he  may  be  obliged 
to  continue  his  new  reginu-n  as  long  as 
he  lives. 

Fi  H!.  Foons 

What  shall  we  say  of  the  fuel  foods  ? 
These  enter  the  body,  not  to  become  an 
enduring  j)arl  of  it,  but  to  be  oxidized 
to  suj>i)ly  current  needs.  \\\'  ha\«'  im- 
plied that  wlicn  this  is  the  service  to  be 
performed  the  >)il).st itution  of  one  typ«' 
of  fo(Kl  for  another  can  be  (juite  freely 
j)ractise(l.  The  ob\ious  (juotion  is  as  to 
whether  any  lixed  |)roporlion  between 
fat.s  and  cari)o-h>(lrates  can  lie  decisi\-ely 
recommended;  but  ai>out  this  matter  it 
seems  impo>>ible  to  make  dogmatic 
statements;  tlie  ratio  lia>  to  be  deter- 
mined largely  by  indixidual  taNte>  and 
the  capacity  of  tin'  subject  to  a>>imi!ate 
J  2 


AN  ADEQUATE  DIET 

one  kind  or  tho  other.  There  is  also  an 
eeononiie  eonsich'ration ;  ear))<)-h ydrates 
are,  in  general,  mueli  eheaper  than  fats. 
Tlie  faet  is  familiar  to  tlie  dietitian 
that  fats  and  earl)o-liy(irates  liave  very 
different  fuel  values.  If  an  ounce  of  fat 
is  to  he  rei)Iaced  with  earho-hydrate,  it 
will  not  answer  to  su|)j)ly  an  ounce  of  the 
latter;  it  will  take  more  than  twice  as 
much  to  provide  equivalent  energy.  The 
technical  statement  is  that  a  given 
weight  of  fat  is  {,so(Iij)t(n)tic  with  about 
two  and  a  quarter  times  as  much  starch. 

Starch  and  Sugar 

A  word  may  be  said  about  the  differences 
between  starch  and  sugar.  These  two 
orders  of  carbo-hydrates  are  nearly  re- 
lated; in  the  plant  world  the  change  of 
one  into  the  other  is  continually  taking 
place.  The  starches  are  relatively  in- 
soluble; the  sugars  dissolve  freely.  In 
the  course  of  digestion,  starch  is  changed 
to  sugar.  The  student,  on  learning  this, 
43 


HARVARD  HIIVLTII  TALKS 

naturally  asks  why  tho  supir  niiglit  not 
have  been  eaten  instead  of  the  starch, 
and  the  digestive  transfonnation  omit- 
ted, but  reasons  for  preferring  to  use  a 
good  (leal  of  starch  are  not  dinicult  to 
find. 

Highly  soluble  bodies  are  always  irri- 
tating to  living  membranes.  This  is 
readily  recognized  in  the  case  of  salts. 
In  the  ca.se  of  the  sugars,  it  is  really 
demonstrated  by  their  sweetness;  for 
tlie  stinuilation  ()f  the  organs  of  taste  is 
an  example  of  irritation.  Starch,  which 
does  not  give  rise  to  sensations  of  taste, 
is  correspondingly  unstinnilating  to  the 
cells  in  general.  The  formation  of  sugar 
from  starch  in  the  canal  is  a  relatively 
gradual  process  and  cannot  j)roduce  a 
concentrated  solution,  i)rovided  absorp- 
tion fairly  k«'ep.s  j)ace  with  it.  The  ad- 
vantages of  starch  over  sugar  as  the  chief 
carbo-hydrate  of  the  diet  >ho\ild  be 
ai)parent. 


44 


AN  ADEQUATE  DIET 

AlXOlIOL 

Is  regularly  consunit'd  by  millions  of 
human  bcinj^'s  in  cinantitics  wliich  ^'ivc  it 
a  material  imi)orlanc('  in  the  (lift.  A 
recent  writer  (Dodge)  j)oints  out  that 
alcohol  makes  a  larger  coulril)ution  to 
the  fuel  value  in  multitudes  of  cases  than 
protein  does.  This  is  likely  to  be  true 
whenever  the  daily  consumi)tion  of  al- 
cohol is  in  excess  of  two  ounces.  Peoi)le 
who  use  alcohol  to  this  extent  presum- 
ably eat  less  carbo-hydrate  and  fat  than 
tliey  would  if  abstaining;  otherwise, 
they  would  become  corpulent.  To  admit 
that  alcohol  may  })ear  its  part  among  the 
otlierfuels,is  not  to  ignore  thedrawbacks 
and  j)ossible  dangers  of  its  inclusion. 

Over-  and  rxDER-FEEDiXG 

Finally,  we  may  give  some  attention  to 
the  results  of  general  over-  and  under- 
feeding. ^Ye  have  already  discussed 
liigh  and  low  protein  standards.  It 
4.-) 


HARVARD  HEALTH  TALKS 

remains  to  compare  tlie  etTects  of  exces- 
sive and  deficient  calorilic  sui)i)ly.  Cer- 
tain persons  are  reputed  to  he  larp' 
eaters  and  others  to  get  aU)ng  with  a 
htth'.  No  douht,  we  usually  exaj^'gerate 
the  degree  of  contrast,  hut  moderate 
(htferences  apfx-ar  to  exi>t.  One  j)erson 
nuiy  hve  upon  a  scah*  of  twenty-five 
hundred  calories,  while  another,  with 
similar  "  huild  "  and  occu|)ation,  nuiy 
find  two  thousand  siifheient. 

Numerous  experinunls  have  shown 
that  what  is  called  the  "  l>a>al  metahol- 
ism  "  -  the  energy  rcfiuirenicnt  during 
rest  and  fa>ling-  does  not  var>  much 
among  healthy  >ui)je(fs.  There  are 
prohahly  more  distiml  pergonal  difTi-r- 
ences  when  work  is  jxrformed  or  htw 
temperatures  are  ene(»untered.  Some 
organisms  may  !»«■  more  economical  and 
♦•f!ici«nt  than  others.  Wiieii  we  set-  a 
florid  man.  we  are  apt  to  gues>  that  he  !s 
a  hea\y  eater.  It  is  j>ONsihlc  that  he 
has  inherited  a  sy>l(in  which  is  prodigal 
Hi 


AN  ADEQUATE  DIET 

in  dispersing  heat,  and  that  his  dietetic 
habits  are  necessary  to  its  upkeep.  If 
it  is  true  that  such  conditions  occur,  they 
may  remind  us  of  the  poorly  built  and 
draughty  houses  wliich  call  for  such  a 
great  consunij)tion  of  coal  to  warm 
them. 

If  we  grant  tliat  some  people  need 
more  food  than  others  under  like  cir- 
cumstances we  have  still  one  important 
indication  to  consider,  namely,  body- 
weight.  The  reliability  of  appetite  is 
impressively  shown,  in  the  great  ma- 
jority of  cases,  by  the  constancy  of  the 
weight  through  long  terms  of  years.  A 
very  small  surplus  of  income  over  oxida- 
tion, day  by  day,  will  soon  result  in 
obesity,  while  an  equally  small  deficit 
will  lead  to  emaciation.  It  is  not 
strange  that  these  imperfect  adjust- 
ments should  be  frequently  observed. 
The  most  common  instance  is  the  per- 
sistence of  an  appetite  suited  to  an 
active  life  into  years  of  lessening  oxida- 
47 


HARVAHI)  IIKALTH  TALKS 

tion.  The  resulting  increase  of  weight  is 
in  every  way  undesiralde. 

Wliat  are  the  characterislies  of  the 
<.)Ver-fe(l  and  tlic  undt-r-fed  ?  ^^hile 
there  are  j)ri)l)al)Iy  exceptions  to  the 
ruh',  the  two  ty])e>  may  l)e  expected  to 
appear  sonn-wliat  as  follows.  The  fir>t 
is  lieavy,  and  of  a  high  color.  The  man 
of  this  class  is  a  deep  slee]>er,  and  dislikes 
to  gi-t  nj);  he  is  an  optimist,  hut  not 
remarkahly  jxT'-evering.  'Ihe  sjjaringly 
fed  indi\idual  is  consistently  opjxoed  to 
the  liherally  noiiri^lnd  at  cNcry  j)oint. 
He  is  under  weight,  and  often  dt  lici<nt 
in  color;  a  light  sleeper,  if  not  a(  luall>' 
trouhled  l»y  inxiinnia;  and  seii>iti\-e  to 
cold.  As  a  Worker  lu-  may  he  diligent 
and  eflicienl,  tlumgh  the  temperament 
exhil)it<'d  is  likely  to  he  (dnseieiili<uis 
rather  than  enthusiastic. 

The  high  degree  of  endurance  often 
noted  in  men  an<l  women  who  eat  liglill\' 
atfords  file  strongest  ai-gunuiit  in  fa\(>r 
of  sucli  self-denial.     It  is  prohahl}"  to  In- 

IS 


AN  ADEQUATK  DIET 

explained  by  two  eireuiiistanees.  First, 
tlie  intestine  is  to  an  exceptional  decree 
free  from  injurious  residues.  Second,  tlie 
blood  and  other  body-fluids  are  eorre- 
spondin^dy  free  from  avoidable  l)y-pro- 
duets  of  metabolism.  The  resistance  to 
fatigue  secured  is  j^reatly  to  be  coveted, 
but  it  is  not  unlikely  that  the  cutting 
down  of  the  food  is  often  too  rigorous. 
Depression  of  spirits  is  a  common  sign 
that  the  diet  should  be  made  more 
generous. 


49 


HARVARD  HEALTH  TALKS 

A  Few  Refeuences 

Liisk,  The  Fundamental  Basis  of  Nutri- 
tion.   Yale  Univorsity  Press,  1914. 

MciuK'l,  Changes  in  Food  Supply.  Yale 
University  Press,  1!)15. 

Sheniian,  Food  Produets.  Macinillan, 
New  York,  1914. 

Bailey,  Source,  Chemistry,  and  Use  of 
Food  Products.  Blakiston,  Pliiladel- 
phia,  1914. 

Meltzer,  "  The  Factors  of  Safety  in  the 
Animal  Structure  and  Economy," 
Jour,  of  Amcr.  Med.  Assoc,  1907, 
vol.  xlviii,  p.  655. 

Chittenden,  Physiological  Economy  in 
\idrition.   Stokes,  New  York,  1904. 

Lusk,  Elements  of  the  Science  of  Nidrition. 
Saunders,  Philadelphia,  1909. 


51 


rUSTtl)    AT 

lUr    UARVARD    INlVtLsrTY    PEKiS 

CAUilBUK^K     MASS  ,    C    S    A . 


nivrivA 


